In a heavy-bottomed saucepan over medium heat, melt unsalted butter and swirl until it turns a rich amber color, about 5-7 minutes. Let it cool for 15-30 minutes before using.

Blot any excess moisture from the pumpkin puree using a clean cloth or paper towel and set aside.

In a large mixing bowl, whisk together all-purpose flour, pumpkin spice blend, baking soda, and salt until evenly combined.

In a separate bowl, stir the cooled brown butter with brown sugar and pure maple syrup until smooth. Mix in egg yolk, prepared pumpkin, and vanilla extract.

Gently fold the dry ingredients into the wet mixture until just combined. Cover and chill the dough in the refrigerator for at least 8 hours or overnight.

Preheat your oven to 350°F (177°C) and line baking sheets with parchment paper.

Roll chilled dough into 2-inch balls and roll in the spiced sugar mixture. Place on prepared baking sheets.

Bake cookies for 12-14 minutes until golden around the edges. If they puff excessively, lightly bang the baking sheet against the oven rack.

Cool cookies on the baking sheet for 3-5 minutes before transferring to a cooling rack.